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WO1995016817A1 - Tamis - Google Patents

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Info

Publication number
WO1995016817A1
WO1995016817A1 PCT/SE1994/001045 SE9401045W WO9516817A1 WO 1995016817 A1 WO1995016817 A1 WO 1995016817A1 SE 9401045 W SE9401045 W SE 9401045W WO 9516817 A1 WO9516817 A1 WO 9516817A1
Authority
WO
WIPO (PCT)
Prior art keywords
rod
screen device
profiles
rod profiles
screen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SE1994/001045
Other languages
English (en)
Inventor
Peter Olsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Metso Fiber Karlstad AB
Original Assignee
Kvaerner Pulping Technologies AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kvaerner Pulping Technologies AB filed Critical Kvaerner Pulping Technologies AB
Priority to AU12855/95A priority Critical patent/AU1285595A/en
Publication of WO1995016817A1 publication Critical patent/WO1995016817A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C7/00—Digesters
    • D21C7/08—Discharge devices

Definitions

  • the invention described here is a screen device which is primarily intended to be used when displacing liquid through a chip bed.
  • the preferable field of application is the withdrawal of cooking liquid when producing chemical paper pulp in a continuous digester.
  • Present-day screens usually consist of rod screen sections which are often arranged in a chessboard-like pattern at the desired positions in the digester wall.
  • Each "chessboard square” consists of a multiplicity of vertically arranged rods. Between each rod there is a gap through which liquid can be withdrawn.
  • the rods are fixed in parallel at crossbars and the screen is provided with a frame of L iron (see Fig. 1) .
  • the invention is based on the simple but ingenious idea of turning each screen part through 90° so that the rods become horizontal.
  • each rod profile is provided with a bevel, shaped so that a widening in the cross-sectional area of the digester is formed before the chip bits meet a new rod profile. This prevents the chip bits from directly encountering an edge when they leave the rod situated above during their journey downwards.
  • the great advantage of a screen element in accordance with the invention is that the digester, equipped with such a screen, will not be found to be so difficult to operate as is currently the case.
  • the cooking process can be optimized so that the fibres, when departing from the digester, have such strength properties that they are able to survive the novel, environmentally friendly, bleaching methods.
  • Figure 1 shows a previously known screen element.
  • Figure 2 shows the section A-A in Figure 1.
  • Figure 3 shows a screen element which is preferred in accordance with the invention.
  • Figure 4 shows the section B-B in Figure 3.
  • Figure 1 shows a known method of arranging a screen element.
  • This screen element consists of a multiplicity of rod profiles which are fixed, vertically and parallel to each other, at a number of crossbars.
  • the height of the screen element is typically in the order of size of 500 mm.
  • Figure 2 shows a cross-section indicating how the rods 2 in a known screen element 1 typically appear and how these rods are joined to the crossbars 3, which are in turn fixed to a frame of L iron 4. Steel is normally used in all parts and the method of assembly is welding. Note especially that the cross-sectional profile of the rods is symmetrical on each side of their vertical axis and that the surface of the screen facing in towards the centre of the digester is completely plane.
  • FIG 3 shows a preferred embodiment of a screen element according to the invention.
  • the screen 5 is essentially rectangular and consists, in this case too, of a multiplicity of rod profiles 6 which are fixed, parallel to each other, at a number of crossbars 7, which expediently consist of flat bar steel. These crossbars are then, like the short sides of the rod profiles, fastened to a frame of L iron 8.
  • the method of joining is preferably welding and the parts included in the screen section are preferably manufactured from steel.
  • the difference from the known embodiment is that the rods are arranged horizontally in the digester wall, that is perpendicular to the longitudinal axis of the digester.
  • the rod profiles 6 according to the invention are bevelled at a given angle a ⁇ , which can be optimized, between the normal to the surface 9 and the horizontal plane, so that the screen assumes a wash-board-like appearance.
  • the angle a ⁇ is between 0 and 30°, preferably 10-20° and more preferably approximately 15°.
  • the cross- sectional profile of the rods is not symmetrical.
  • the surface of the screen is arranged so that an imaginary vertical line intersects the surface 9 of the rod profiles at essentially the same point on each rod.
  • the gap between the rods is such that it at least does not decrease, seen from the surface of the screen facing in towards the digester, and radially outwards.
  • This is expediently brought about by the rod profiles being provided, at their surface facing in towards the chip bed, with a lip 10 at the bottom.
  • the surface 9 of each rod profile is terminated in a sharp manner by the lower edge of the lip 10 being designed with a distinct angle a 2 .
  • the transition section between the upper edge of the rod profiles 6 and the bevelled edge 9 can be rounded in order to provide a mild treatment for the chips.
  • the radius is then at most equal to half the thickness t of the rod profile, preferably approx ⁇ imately 30% of the thickness t of the rod profile. This embodiment is shown in principle in the lowest rod profile in Figure 4.

Landscapes

  • Paper (AREA)

Abstract

L'invention concerne un tamis utilisé lors du déplacement d'un liquide à travers un lit de copeaux relatif, de préférence, au retrait d'un liquide de cuisson dans un lessiveur continu servant à fabriquer de la pâte à papier chimique. Ledit tamis (5) est, de préférence, rectangulaire et construit à partir d'une multiplicité de tiges profilées (6), fixées parallèlement les unes par rapport aux autres à plusieurs barres transversales (7). La longueur desdites tiges profilées (6) se situe à l'horizontale et elles présentent, dans leur totalité, une surface gondolée dirigée vers le lit de copeaux. Cet effet provient du fait que la surface de chaque tige (6) dirigée vers le lit de copeaux est biseauté selon un angle déterminé, pouvant être optimisé, de telle manière que la section transversale du lessiveur s'élargit avant chaque tige suivante du haut vers le bas.
PCT/SE1994/001045 1993-12-16 1994-11-08 Tamis Ceased WO1995016817A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU12855/95A AU1285595A (en) 1993-12-16 1994-11-08 Screen device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9304177-0 1993-12-16
SE9304177A SE501243C2 (sv) 1993-12-16 1993-12-16 Silanordning

Publications (1)

Publication Number Publication Date
WO1995016817A1 true WO1995016817A1 (fr) 1995-06-22

Family

ID=20392116

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1994/001045 Ceased WO1995016817A1 (fr) 1993-12-16 1994-11-08 Tamis

Country Status (3)

Country Link
AU (1) AU1285595A (fr)
SE (1) SE501243C2 (fr)
WO (1) WO1995016817A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU669274B2 (en) * 1993-02-16 1996-05-30 Kvaerner Pulping Technologies Ab Straining device
US6039841A (en) * 1995-02-23 2000-03-21 Ahlstrom Machinery Inc. Screen having inclined slots for use in a continuous digester
US6165323A (en) * 1999-02-10 2000-12-26 Andritz-Ahlstrom Inc. Screen plate having a plurality of inclined slots in a digester
WO2009070115A1 (fr) 2007-11-30 2009-06-04 Metso Fiber Karlstad Ab Tamis de lessiveur pour un lessiveur de pâte de cellulose continu
US8980061B2 (en) 2012-01-12 2015-03-17 Valmet Ab Profile bar screen for digester vessels
US10087579B2 (en) 2014-09-01 2018-10-02 Valmet Ab Profile bar screen for digester vessels

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2998064A (en) * 1957-12-11 1961-08-29 Improved Machinery Inc Strainer construction
US3385753A (en) * 1967-05-15 1968-05-28 Improved Machinery Inc Strainer
US3752319A (en) * 1970-09-24 1973-08-14 Kamyr Ab Strainer device in a continuous cellulose digesting plant

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2998064A (en) * 1957-12-11 1961-08-29 Improved Machinery Inc Strainer construction
US3385753A (en) * 1967-05-15 1968-05-28 Improved Machinery Inc Strainer
US3752319A (en) * 1970-09-24 1973-08-14 Kamyr Ab Strainer device in a continuous cellulose digesting plant

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU669274B2 (en) * 1993-02-16 1996-05-30 Kvaerner Pulping Technologies Ab Straining device
US6039841A (en) * 1995-02-23 2000-03-21 Ahlstrom Machinery Inc. Screen having inclined slots for use in a continuous digester
US6344112B1 (en) 1995-02-23 2002-02-05 Andritz-Ahlstrom Inc. Screen having inclined slots for a digester
US6165323A (en) * 1999-02-10 2000-12-26 Andritz-Ahlstrom Inc. Screen plate having a plurality of inclined slots in a digester
WO2009070115A1 (fr) 2007-11-30 2009-06-04 Metso Fiber Karlstad Ab Tamis de lessiveur pour un lessiveur de pâte de cellulose continu
US8980061B2 (en) 2012-01-12 2015-03-17 Valmet Ab Profile bar screen for digester vessels
US10087579B2 (en) 2014-09-01 2018-10-02 Valmet Ab Profile bar screen for digester vessels

Also Published As

Publication number Publication date
SE9304177L (sv) 1994-12-19
SE9304177D0 (sv) 1993-12-16
AU1285595A (en) 1995-07-03
SE501243C2 (sv) 1994-12-19

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